# Effect of Hand Grip Strength on Perioperative Outcomes in Older Female Patients Scheduled for Total Knee Arthroplasty Under General Anesthesia—A Prospective Observational Study

## TL;DR

This study found that lower hand grip strength in older women before knee surgery is linked to a higher risk of postoperative delirium.

## Contribution

The study identifies preoperative hand grip strength as a novel predictor of postoperative delirium in older female patients undergoing knee surgery.

## Key findings

- Lower hand grip strength was significantly associated with increased postoperative delirium in older female patients.
- Each 1 kg increase in hand grip strength reduced the risk of delirium by 28%.
- Hand grip strength was the only factor affecting delirium in multivariate analysis.

## Abstract

Background: This study aims to evaluate the effect of hand grip strength (HGS) on perioperative outcomes—particularly postoperative delirium (POD)—in patients scheduled for total knee arthroplasty (TKA). Methods: Older female patients, aged ≥ 65 years, who were scheduled for TKA under general anesthesia were enrolled in this study. We measured preoperative HGS and clinical frailty scale. The primary outcome was the incidence of POD within 30 days of surgery. Secondary outcomes included intraoperative hypotension, surgical site infection, postoperative pulmonary complications, postoperative nausea and vomiting, acute kidney injury, postoperative urinary retention, and hospital length of stay. Results: The final analysis was conducted on 78 participants. The median HGS was 17.9 kg, the patients were divided into Weak (HGS ≤ 17.9, n = 39) and Strong groups (HGS > 17.9, n = 39). POD was more prevalent in the Weak group (23.1% vs. 0.0%, p = 0.005). As secondary outcomes, there were no significant differences between the two groups, except the postoperative estimated glomerular filtration rate (101 [90; 120.5] mL/min/1.73 m2 in the Weak group vs. 122 [104; 138] mL/min/1.73 m2 in the Strong group; p = 0.007). In the receiver operating characteristic curve analysis of POD occurrence according to HGS, the cutoff value was 17.5 (area under curve 0.88, p < 0.001). In univariate logistic regression analysis, age and HGS were associated with the occurrence of POD. In multivariate logistic regression analysis, HGS was the only factor that affects POD. For each 1 kg increase in HGS, the risk of POD decreased by 28% (Odds ratio: 0.72). Conclusions: In this study, lower preoperative HGS was significantly associated with the occurrence of POD.